BT CALLMINDER ANALOGUE/DIGITAL FAULT

[Puzzled!]

PLEASE can anyone out there help restore our call minder when BT and Openreach have failed to do so in three months? We lost this facility in April, after we lost the power to our house for about five minutes during a storm. To cut a VERY long story short, we have bought new phones, had at least six visits from engineers and we now have callminder on an analogue hone which BT kindly supplied. But as we are elderly and I am partially disabled, we really do need the digital phones to work, so any seriously helpful suggestions would be most useful! The engineers are at a loss as to what to do next.
Thank you all

[Puzzled!]

sorry - it is the caller ID we have lost!